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topic 5873

Need Help Using Muriatic Acid to Rust Sheet Metal


Q. I have started a new welding business doing yard ornaments. I used muriatic acid at full strength on one of my designs and did not wash it off, it did rust the metal, but left streak marks and a few medium sized black marks. A few others that I did, I washed off the acid with water, and they too rusted but also had streaks.

How do I get a finish that will give me an even or semi-even finish without the streaks or black marks? The metal I am using it on is 12 gauge sheet metal. I would appreciate any help I can get!

Thank you Sally

Sally Dowell
Designer Welding - Shelbina, Missouri


A. Try diluting the acid by 10, then add a teaspoon of table salt/gallon. Immerse the part, then drip dry.

The acid, at full strength, is too powerful. You can also try other acids, like vinegar (acetic acid), other condiments, like ketchup or mustard, and other salts, like Epsom salt (magnesium sulfate).

pooky tom pullizi signature
Tom Pullizzi
Falls Township, Pennsylvania


A. Try cleaning your work with some strong scouring cleanser to remove any soil which is acting as a resist. You will get a more even result, as Tom suggests, by immersion instead of brushing the acid on.

Another thought: Have you tried sandblasting your work first?

Neil Bell
Red Sky Plating

supporting advertiser
Albuquerque, New Mexico
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A. With regards to cleaning the metal from grease or oily film used for protection on sheet metal, I usually scrub thoroughly with mineral oil until you don't see a film anymore.

Alan Neal
hobbyist - Atlanta, Georgia


Q. I use Muriatic Acid [linked by editor to product info at Amazon] to rust sheet metal also, but need to find a better way to neutralize it after it rusts. Currently using Super Sock It for pools. Also having trouble with black spots when the weather is damp. Because of the amount we do, have to do it outside where we are at the mercy of the weather. What is the best thing to clean the metal (grease applied to prevent rusting) before we dip it?

Thanks for your help!

Alan Bolick
- Jefferson, Texas


Q. I'm looking to create a magnetic post-it board in our studio.

I'd like to purchase a 4'x8' sheet of sheet metal and give it a 'rustic' look by using muriatic acid.

How should I go about doing this?

I'm assuming that it will continue to rust in time as well?

Andy Vanderkaay
- Toronto, Ontario, Canada

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